added docs

CMakeModules/CorsikaUtilities.cmake

@@ -95,9 +95,30 @@ endmacro(CORSIKA_ADD_FILES_ABSOLUTE)
 
 #################################################
 #
-# central macro to activate unit tests in cmake
+# central macro to register unit tests in cmake
 #
-
+# 1) Simple use:
+# Pass the name of the test.cc file as the first
+# argument, without the ".cc" extention.
+#
+# Example: CORSIKA_ADD_TEST(testSomething)
+# (generates target testSomething from file testSomething.cc)
+#
+# 2) Customize sources
+# If 1) doesn't work, use the SOURCES keyword to explicitly
+# specify the sources.
+#
+# Example: CORSIKA_ADD_TEST(testSomething SOURCES source1.cc source2.cc someheader.h)
+#
+# 3) Customize sanitizers
+# You can override which sanitizers are compiled into the
+# test, but only do this if the defaults do not work.
+#
+# Example: CORSIKA_ADD_TEST(testSomething SANITIZE undefined)
+# (only uses the sanitizer for undefined behavior)
+#
+# In all cases, you can further customize the target with
+# target_link_libraries(testSomething ...) and so on.
 function (CORSIKA_ADD_TEST)
   cmake_parse_arguments(PARSE_ARGV 1 _ "" "SANITIZE" "SOURCES")